JPH10341180A - Broadcast signal receiving method and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To selectively receive the satellite broadcast or cable TV signals by filtering the phase shifted combination signals at the prescribed 3rd filtering frequency and producing a base band Q signal of the satellite broadcast signal corresponding to the selected channel. SOLUTION: A shifter 217 receives a 3rd oscillation signal from a 2nd local oscillator 215 and outputs the oscillation signal to a 3rd mixer 221 after shifting the phase of the oscillation signal by 90 degrees. The mixer 221 combines the output signal received from an SAW filter passing through an AGC 211 and an AMP 213 with the phase shifted 3rd oscillation signal to produce a phase shifted 3rd IF signal. This IF signal is supplied to a 2nd LPF 233 via an AMP 225. The LPF 233 filters the received IF signal at the prescribed cut-off frequency and produces a base band Q signal of 16 MHz.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a broadcast signal receiving system, and more particularly, to an improved broadcast signal receiving method and apparatus capable of selectively receiving a satellite broadcast signal or a cable TV signal.

[0002]

2. Description of the Related Art Broadcasting systems such as satellite broadcasting and cable TV have recently been widely used with the rapid development of new media.

[0003] A satellite broadcast system can transmit a broadcast signal to a wider area than other broadcast systems using a satellite located about several hundred kilometers from the ground.

[0004] Usually, a satellite broadcasting system sends out a satellite broadcasting signal having a frequency of 11.7 GHz to 12.2 GHz having a plurality of channel signals. The transmitted satellite broadcast signal is received by a low noise block down converter (LNBC) attached to a parabolic antenna and processed for subsequent signal processing (eg,
It is converted to a radio frequency (RF) signal of 950-2050 MHz for the tuning of certain channel signals). This converted RF signal is input to a tuner incorporated in a satellite broadcast signal receiver attached to a TV receiver. A satellite broadcast signal receiver provided with a tuner having a tuning frequency of 950 to 2050 MHz tunes and receives a predetermined channel signal from the converted RF signal. Normally, each channel signal included in the converted RF signal has a bandwidth of 32 MHz.

FIG. 1 is a schematic block diagram of a conventional satellite broadcast signal receiver. As shown in FIG. 1, the satellite broadcast signal receiver includes two amplifiers AMP101 and 109, a bandpass filter (BPF) 103, and first and second local oscillators 10.
5, 115 and the first, second and third mixers 107, 119,
121, a surface acoustic wave (SAW) filter 111, an automatic gain controller (AGC) 113, a shifter 117, first and second
And low-pass filters 123 and 125.

[0006] The RF signal converted by the LNBC is input to an amplifier 101, amplified to a predetermined level, and then supplied to a BPF 103 having a band-pass filtering frequency of 950 to 2050 MHz. This BPF
The filter 103 filters the amplified RF signal at a band-pass filtering frequency, removes noise contained in the RF signal, and supplies the filtered signal to the first mixer 107. On the other hand, a first local oscillator 105 having a variable oscillation frequency of 1429 to 2530 MHz is provided with a desired channel signal according to an oscillation control signal from a controller (not shown) incorporated in the receiver, for example, a microprocessor. A predetermined oscillation signal for tuning the frequency is generated and supplied to the first mixer 107. The first mixer 107 combines the output signal from the BPF 103 and the oscillation signal from the first local oscillator 105 to generate a first intermediate frequency (IF) signal of approximately 479.5 MHz. The SAW filter 111 receives the output signal supplied from the first mixer 107 through the AMP 109 and generates a channel signal having a bandwidth of about 32 MHz. The AGC 113 automatically adjusts the gain of the channel signal received from the SAW filter 111, for example, in response to a gain control signal from a video amplifier that supplies a constant level video signal as the output of a video detector (not shown). And the second and third mixers 119,
Output to 121 respectively.

On the other hand, the second local oscillator 115
The 479.5 MHz fixed oscillation signal is supplied to the second mixer 119 and the shifter.
117 to each. The second mixer 119 has an AGC 113
For example, the second IF signal of 0 MHz is detected and supplied to the first LPF 123 by combining the output signal of the second local oscillator 115 and the fixed oscillation signal of the second local oscillator 115. The shifter 117 shifts the phase of the fixed oscillation signal received from the second local oscillator 115 by 90 ° and supplies it to the third mixer 121.
The third mixer 121 combines the output signal from the AGC 113 and the phase-shifted oscillation signal from the shifter 117 to detect a 0-MHz phase-shifted IF signal, and outputs a second L signal.
Supply to PF125.

[0008] Finally, the first LPF 123 is a second mixer.
The output signal from 119 is filtered at a predetermined cutoff frequency to generate a 16 MHz baseband I signal,
The second LPF 125 filters the output signal from the third mixer 121 with a predetermined cutoff frequency to obtain a 16 MHz signal.
Generate a baseband Q signal of z. These baseband I and Q signals are used in subsequent processors (not shown) for demodulation for visible display.

On the other hand, as is well known, the cable TV broadcasting system transmits, for example, a cable TV signal in a band of 54 to 860 MHz to a cable TV signal receiver attached to a TV receiver through a coaxial cable. This cable TV signal is composed of a plurality of channel signals each having a bandwidth of 6 MHz. Further, like the components of the satellite broadcast signal receiver, the cable TV signal receiver also includes a BPF, a mixer, a local oscillator, a SAW filter, and the like.

However, as described above, in order to receive a satellite broadcast signal and a cable TV signal, both the satellite broadcast signal receiver and the cable TV signal receiver are similar in structure, but both the TV receiver and the television receiver are similar. The additional arrangement has a disadvantage of complicating the structure of the device and increasing the cost.

[0011]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a broadcast signal receiving method and apparatus capable of selectively receiving a satellite broadcast signal or a cable TV signal.

[0012]

According to an embodiment of the present invention, there is provided a broadcast signal receiving method for selectively receiving a satellite broadcast signal or a cable TV signal, comprising the steps of: When a channel to be tuned is selected, a first step of generating a first oscillation signal having a predetermined first oscillation frequency according to a first oscillation control signal supplied from a controller; Receiving a first oscillation signal and one of the satellite broadcast signal and the cable TV signal and combining the received signals to generate a first combined signal having a first intermediate frequency (IF) signal; B) performing a filtering on the first combination signal at a predetermined first filtering frequency to generate a waveform band signal; and When a broadcast mode signal indicating a type of a broadcast signal to be tuned to the transmission signal or the cable TV signal is selected, a predetermined second oscillation control signal is supplied according to a second oscillation control signal supplied from the controller. A d-step of selectively generating a second oscillation signal having a frequency or a third oscillation signal having a predetermined third oscillation frequency; and forming the waveform band signal and the second or third oscillation signal. Receiving and combining the received signals to form a second IF
E) outputting a second combination signal having a second signal or a third combination signal having a third IF signal, and converting the second combination signal to a predetermined second signal according to the broadcast mode signal.
Or f) selectively filtering at a third filtering frequency to generate a channel signal of the cable TV signal or a baseband I signal of the satellite broadcast signal corresponding to the selected channel; 3 The phase of the oscillation signal is shifted by a predetermined angle,
Generating a phase shifted third oscillation signal, combining the waveform band signal and the phase shifted third oscillation signal, and forming a phase shifted combination signal having a phase shifted third IF signal; And filtering the phase-shifted combined signal at the third predetermined filtering frequency to generate a baseband Q signal of the satellite broadcast signal corresponding to the selected channel. And a method for receiving a broadcast signal.

According to another embodiment of the present invention, there is provided a broadcast signal receiving apparatus for selectively receiving a satellite broadcast signal or a cable TV signal, wherein when a channel to be tuned by a user is selected, a controller is provided. A first signal generating means for generating a first oscillation signal having a predetermined first oscillation frequency in accordance with a first oscillation control signal supplied from the control unit, the first oscillation signal, the satellite broadcast signal or The cable T
V signal receiving means for receiving any one of the V signals and combining the received signals to generate a first combination signal having a first intermediate frequency (IF) signal; Third signal generating means for filtering a signal at a predetermined first filtering frequency to generate a waveform band signal; and a broadcast to be tuned by the user to the satellite broadcast signal or the cable TV signal. When a broadcast mode signal representing a type of signal is selected, a second oscillation signal having a predetermined second oscillation frequency, or a predetermined second oscillation signal, according to a second oscillation control signal supplied from the controller. Third having a third oscillation frequency
Fourth signal generating means for selectively generating an oscillating signal; receiving the waveform band signal and the second or third oscillating signal; combining the received signals to form a second signal having a second IF signal; A third signal having a combination signal or a third IF signal
Fifth signal generating means for outputting a combination signal, and selectively filtering the second combination signal at a predetermined second or third filtering frequency according to the broadcast mode signal. A sixth signal generating means for generating a channel signal of the cable TV signal or a baseband I signal of the satellite broadcast signal corresponding to the selected channel, and adjusting the phase of the third oscillation signal by a predetermined angle. Generating a phase shifted third oscillation signal, combining the waveform band signal and the phase shifted third oscillation signal, and generating a phase shifted third IF signal having a phase shifted third IF signal. Generating a combined signal having undergone the phase shift, filtering the combined signal having undergone the phase shift with the third predetermined filtering frequency, and providing the satellite broadcast corresponding to the selected channel. Seventh broadcast signal receiving apparatus characterized by comprising a signal generating means is provided for generating a baseband Q signal No..

[0014]

Preferred embodiments of the present invention will be described below in detail with reference to the drawings. In FIG.
1 shows a block diagram of a broadcast signal receiving device according to the present invention.

As shown in FIG. 2, the broadcast signal receiving apparatus of the present invention comprises first and second BPFs 201 and 229, first and second local oscillators 203 and 215, and first, second and second local oscillators 203 and 215. 3 mixers 205, 219, 221 and 4 AMPs 207, 213
, 223, 225 and a surface acoustic wave (SAW) filter 209
, An automatic gain controller (AGC) 211, a shifter 217, a switching unit 227, and first and second low-pass filters (LP
F) 231 and 233.

A received broadcast signal, for example, a satellite broadcast signal or a cable TV signal frequency-converted by the LNBC is input to the first BPF 201. This first BPF
201 filters a received broadcast signal having a converted RF signal or a cable TV signal, for example, a frequency of 54 to 2050 MHz at a predetermined band-pass filtering frequency, and removes noise included in the received broadcast signal. It works to remove. Then, the first BPF 201
Supplies the signal from which noise has been removed to the first mixer 205. When a channel to be tuned is selected by the user, a first local oscillator 203 having a variable oscillation frequency of at least 534.75-2530 MHz is provided by a first local oscillator 203, for example, from a controller (not shown) such as a microprocessor. In response to the oscillation control signal, a first oscillation signal for selecting a desired channel signal is generated from the output signal of the first BPF 201 and supplied to the first mixer 205.

The first mixer 205 includes a first BPF 20
1 and the first oscillation signal from the first local oscillator 203 are received, the two signals are combined, and the difference between the two signals is detected as a first IF signal of approximately 479.5 MHz. First IF detected by first mixer 205
The signal is amplified to a predetermined level by an amplifier 207 and then supplied to a SAW filter 209.

The SAW filter 209 filters the signal received from the amplifier 207, generates a 32 MHz waveform band signal, and supplies it to the AGC 211. Then, A
The GC 211 receives a SAW filter 20 based on a gain control signal from a video amplifier (not shown) such that a signal generated from a video detector (not shown) has a constant level.
The gain of the 32 MHz band signal received from 9 is automatically controlled and supplied to the AMP213. Thereafter, the AMP 213 amplifies the gain-controlled band signal and supplies it to the second and third mixers 219 and 221 respectively.

On the other hand, according to the present invention, the second local oscillator
215 should have two constant oscillation frequencies, and if a broadcast mode signal representing the type of broadcast signal to be tuned by the user (ie, a satellite broadcast signal or a cable TV signal) is selected, a signal from the controller In response to the second oscillation control signal, a second oscillation signal of 435.5 MHz or a third oscillation signal of 479.5 MHz is selectively generated and supplied to the second mixer 219 and / or the shifter 217. If the broadcast signal selected by the user is a cable TV signal, a second oscillation signal is supplied to the second mixer 219, and if a satellite broadcast signal is selected, a second oscillation control signal from the controller is provided. , The third oscillation signal is supplied to the second mixer 219 and the shifter 217, respectively.

The second mixer 219 combines the output signal from the amplifier 213 and the second or third oscillating signal from the second local oscillator 215 to generate two kinds of IF signals, for example, 44 MHz.
A second IF signal of z and a third IF signal of 0 MHz are generated. In AMP223, these second or third IFs
Switching unit after the signal is amplified to a predetermined level
227.

According to the present invention, under the control of the switching control signal from the controller according to the user's command, the switching unit 227 converts the amplified second or third IF signal into the second BPF.
229 or the first LPF 231. Specifically, the second IF signal is the second IF signal.
When the signal is input from the mixer 219 through the amplifier 223, the switching unit 227 outputs the second IF signal to the second BPF.
229, and when the third IF signal is input, the third IF signal is supplied to the first LPF 231.

When the second BPF 229 receives the second IF signal through the switching unit 227, the second BPF 229 filters the received second IF signal with another predetermined band-pass filtering frequency, and performs a cable TV channel signal of a 6 MHz base band. Occurs. This cable TV channel signal is used in the subsequent processor (not shown) when demodulating the image signal. On the other hand, when the first LPF 231 receives the third IF signal via the switching section 227, the first LPF 231 filters the received third IF signal at a predetermined cutoff frequency to generate an I signal of a 16 MHz base band.

On the other hand, the shifter 217 includes the second local oscillator 21
5 and receives the third oscillation signal, shifts the phase of the third oscillation signal by 90 °, and outputs the third oscillation signal to the third mixer 221. Thereafter, the third mixer 221 combines the output signal from the SAW filter 209 passing through the AGC 211 and the AMP 213 with the phase-shifted third oscillation signal to generate a phase-shifted third IF signal. The phase-shifted third IF signal is passed through the AMP225 to the second LPF233.
Supplied to The second LPF 233 is the third I received
The F signal is filtered at a predetermined cutoff frequency to generate a 16 MHz baseband Q signal. These baseband I and Q signals are also provided by a subsequent processor (not shown).
Is used when demodulating an image signal.

Although the preferred embodiments of the present invention have been described above, those skilled in the art will be able to make various modifications without departing from the scope of the present invention.

[0025]

As described above, according to the present invention, a satellite broadcast signal or a cable TV signal can be selectively tuned and received, so that the structure of the apparatus can be simplified and the manufacturing cost can be further reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of a conventional satellite broadcast signal receiver.

FIG. 2 is a block diagram of an improved broadcast signal receiving apparatus according to the present invention.

[Explanation of symbols]

 201, 229 BPF 203, 215 Local oscillator 205, 219, 221 Mixer 207, 213, 223, 225 Amplifier (AMP) 209 SAW filter 211 AGC 217 Shifter 227 Switching section 231, 233 LPF

Claims (10)

[Claims] 1. A broadcast signal receiving method for selectively receiving a satellite broadcast signal or a cable TV signal, comprising: (a) when a channel to be tuned by a user is selected, a first signal supplied from a controller; A first step of generating a first oscillation signal having a predetermined first oscillation frequency in response to an oscillation control signal; and (b) generating a first oscillation signal and the satellite broadcast signal or the cable TV signal. Any one of them is received, and both received signals are combined to form a first intermediate frequency (I
F) a second step of generating a first combination signal having a signal; and (c) filtering the first combination signal at a predetermined first filtering frequency to generate a waveform band signal. (D) when the user selects a broadcast mode signal representing a type of a broadcast signal to be tuned to the satellite broadcast signal or the cable TV signal, a second oscillation supplied from the controller; A fourth step of selectively generating a second oscillation signal having a predetermined second oscillation frequency or a third oscillation signal having a predetermined third oscillation frequency in response to the control signal; ) Receiving the waveform band signal and the second or third oscillating signal, combining the received signals,
A fifth step of outputting a second combination signal having an F signal or a third combination signal having a third IF signal; and (f) converting the second combination signal to a predetermined second signal in accordance with the broadcast mode signal. A sixth step of selectively filtering at a second or third filtering frequency to generate a channel signal of the cable TV signal or a baseband I signal of the satellite broadcast signal corresponding to the selected channel.
(G) phase-shifting the phase of the third oscillation signal by a predetermined angle to generate a phase-shifted third oscillation signal, and the waveform-band signal and the phase-shifted Generating a phase-shifted combination signal having a phase-shifted third IF signal, and converting the phase-shifted combination signal to the predetermined third filtering frequency. And generating a baseband Q signal of the satellite broadcast signal corresponding to the selected channel. 2. The broadcast signal receiving method according to claim 1, wherein the waveform band signal is obtained by a surface acoustic wave filter. 3. The method according to claim 1, wherein the predetermined first oscillation frequency is
The broadcast signal receiving method according to claim 1, having a bandwidth of 534.75 to 2530 MHz. 4. The method according to claim 1, wherein the second and third oscillation frequencies are 43
The broadcast signal receiving method according to claim 1, wherein the frequency is 5.5 MHz and 479.5 MHz. 5. A broadcast signal receiving apparatus for selectively receiving a satellite broadcast signal or a cable TV signal, wherein a first oscillation control signal supplied from a controller when a channel to be tuned is selected by a user. In response to the,
First signal generating means for generating a first oscillation signal having a predetermined first oscillation frequency; receiving the first oscillation signal, and any one of the satellite broadcast signal and the cable TV signal Means for combining the received signals to generate a first combined signal having a first intermediate frequency (IF) signal; and converting the first combined signal to a predetermined first filtering frequency. Signal generating means for generating a waveform band signal by performing filtering, and a broadcast mode signal representing a type of a broadcast signal to be tuned to the satellite broadcast signal or the cable TV signal is selected by the user. Then, according to the second oscillation control signal supplied from the controller, a second oscillation signal having a predetermined second oscillation frequency or a third oscillation signal having a predetermined third oscillation frequency. A fourth signal generating means for selectively generating a third oscillation signal having an oscillation frequency; receiving the waveform band signal and the second or third oscillation signal; Fifth signal generating means for outputting a second combination signal having a 2IF signal or a third combination signal having a third IF signal; and a second predetermined combination of the second combination signal according to the broadcast mode signal. Or sixth signal generating means for selectively filtering with a third filtering frequency to generate a channel signal of the cable TV signal or a baseband I signal of the satellite broadcast signal corresponding to the selected channel; The phase of the third oscillation signal is shifted by a predetermined angle to generate a phase shifted third oscillation signal, and the waveform band signal and the phase shifted third signal are generated. Generating a phase shifted combined signal having a phase shifted third IF signal and filtering the phase shifted combined signal at the predetermined third filtering frequency. And a seventh signal generating means for generating a baseband Q signal of the satellite broadcast signal corresponding to the selected channel. 6. The broadcast signal receiving apparatus according to claim 5, wherein said waveform band signal is obtained by a surface acoustic wave filter. 7. The method according to claim 6, wherein the predetermined first oscillation frequency is
The broadcast signal receiving device according to claim 5, wherein the broadcast signal receiving device has a bandwidth of 534.75 to 2530 MHz. 8. The second and third oscillation frequencies are each 43
The broadcast signal receiving device according to claim 5, wherein the frequency is 5.5 MHz and 479.5 MHz. 9. The apparatus according to claim 5, wherein said second signal generating means includes means for filtering said satellite broadcast signal or said cable TV signal at a predetermined band-pass filtering frequency. Broadcast signal receiving device. 10. The broadcast signal receiving apparatus according to claim 9, wherein the predetermined band-pass filtering frequency has a range of 54 to 2050 MHz.